To provide a waste slag particle group hardly consolidated into a large massive material even when being charged and left as it is in a sea area, eluted in water at pH<9 and free from adversely affecting water system environment and ecological system environment.

The method of making the artificial sand having pH secured in neutral zone of 5.8-8.6 in the elution in water includes: adding a reforming material comprising a granular body containing 0.2-2 pts.mass aluminum component expressed in terms of aluminum oxide and at least 5 pts.mass water based solvent into 100 pts.mass slag particle group; crushing and mixing 3 materials to form a reforming layer comprising an aluminum-containing compound on the surface of the particles of the slag particle group by the double decomposition reaction; and if necessary, dehydrating to reform the surface of the sand like slag particle group. The artificial sand reformed in this way is provided.